1Pamtojpeg2k User Manual(0)                          Pamtojpeg2k User Manual(0)
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NAME

6       pamtojpeg2k - convert PAM/PNM image to a JPEG-2000 code stream
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SYNOPSIS

10       pamtojpeg2k [-imgareatlx=column] [-imgareatly=row] [-tilegrdtlx=column]
11       [-tilegrdtly=row]        [-tilewidth=columns]        [-tileheight=rows]
12       [-prcwidth=columns]        [-prcheight=rows]       [-cblkwidth=columns]
13       [-cblkheight=rows]   [-mode={integer|int|real}]    [-compression=ratio]
14       [-ilyrrates=ratestring]          [-numrlvls=number]          [-progres‐
15       sion={lrcp|rlcp|rpcl|pcrl|cprl}]  [-numgbits=number]  [-nomct]   [-sop]
16       [-eph]  [-lazy]  [-termall]  [-segsym] [-vcausal] [-pterm] [-resetprob]
17       [-verbose] [-debuglevel=number] filename
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19       Minimum unique abbreviation of option is acceptable.  You may use  dou‐
20       ble  hyphens  instead  of single hyphen to denote options.  You may use
21       white space in place of the equals sign to separate an option name from
22       its value.
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DESCRIPTION

27       This program is part of Netpbm(1).
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29       pamtojpeg2k  converts the named PBM, PGM, PPM, or PAM file, or Standard
30       Input if no file is named, to a JPEG-2000 code  stream  (JPC)  file  on
31       Standard Output.
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33       The  JPEG-2000  specification  specifies  two separate formats: JP2 and
34       JPEG-2000 code stream (JPC).   JP2  represents  a  visual  image  quite
35       specifically,  whereas  JPC is a more or less arbitrary array of codes.
36       pamtojpeg2k can't produce a JP2, but the  JPC  image  that  pamtojpeg2k
37       produces  is  very  similar to a JP2 if the input is a PBM, PGM, or PPM
38       image or equivalent PAM image.  One difference is that the  RGB  inten‐
39       sity  values in a JP2 are SRGB values, while pamtojpeg2k produces ITU-R
40       Recommendation BT.709 values.  Those are very similar, but not  identi‐
41       cal.   Another  difference  is that a JP2 can contain extra information
42       about an image that JPC cannot.
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44       When the input is a PAM image other than a PBM, PGM, or PPM equivalent,
45       the  JPC raster produced contains whatever the PAM raster does.  It can
46       have any number of planes with any meanings; the planes are in the same
47       order in the JPC output as in the PAM input.
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49       A  JPC  image  has  a "precision," which is the number of bits used for
50       each code (in Netpbm lingo, "sample").  Actually,  it  has  a  separate
51       precision  for  each  component.  pamtojpeg2k uses for the precision of
52       every component the least number of bits that can represent the  maxval
53       of  the  input image.  A JPC image does not have an independent concept
54       of maxval; the maxval of a JPC sample is the  maximum  value  that  the
55       number  of bits specified by the precision can represent in pure binary
56       code.  E.g. if the precision is 4, the maxval is 15.  pamtojpeg2k  does
57       of  course  scale the sample values from the input maxval to the output
58       maxval.  Example: The input maxval is 99.  This means JPC precision  is
59       7  bits  and  the JPC maxval is 127.  A sample value of 33 in the input
60       becomes a sample value of 43 in the output.
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62       pamtojpeg2k generates the JPC output with the Jasper JPEG-2000  library
63http://www.ece.uvic.ca/~mdadams/jasper/⟩  .   See documentation of the
64       library for details on what pamtojpeg2k produces.  Note that the Jasper
65       library  contains  facilities  for  reading PNM images, but pamtojpeg2k
66       does not use those.  It uses the Netpbm library instead.  Note that the
67       makers  of  the Jasper library write it "JasPer," but Netpbm documenta‐
68       tion follows standard American English typography  rules,  which  don't
69       allow that kind of capitalization.
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71       Use jpeg2ktopam to convert in the other direction.
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73       The  program  jasper,  which  is  packaged  with  the  Jasper JPEG-2000
74       library, also converts between JPEG-2000 and PNM formats.  Because it's
75       packaged  with  the  library,  it  may  exploit  it  better, especially
76       recently added features.  However, since it does  not  use  the  Netpbm
77       library  to  read and write the Netpbm formats, it doesn't do as good a
78       job on that side.
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80       Another format with goals similar to those of JPEG-2000 but that allows
81       for    faster    encoding    and    decoding,   is   JPEG-LS.    CharLS
82http://charls.codeplex.com⟩  is a package of software for using  JPEG-
83       LS.
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OPTIONS

88       Most  of the options are identical in name and function to options that
89       the  Jasper  library  JPC  encoder  subroutine   takes.    See   Jasper
90       documentation  ⟨http://www.ece.uvic.ca/~mdadams/jasper/⟩   for details.
91       Here, we document only options that are not direct  analogs  of  Jasper
92       options.
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97       -compression=ratio
98              ratio  is a floating point number that specifies the compression
99              ratio.  pamtojpeg2k will adjust quality as necessary  to  ensure
100              that  you  get  this compression ratio.  E.g. 4 means the output
101              will be about one fourth the size in bytes of the input file.
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103              The ratio concerns just the raster part of the image,  with  the
104              denominator  being what the raster would take if it were encoded
105              the most naive way possible (e.g. 3 bytes per  pixel  in  8-bit-
106              per-sample  RGB).   It  does,  however, include metadata that is
107              part of the compressed raster.  Because of that, it may  not  be
108              possible  to  give  you  your requested compression ratio at any
109              quality.  If it isn't, pamtojpeg2k fails with a  message  saying
110              so.
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112              If you don't specify this option, pamtojpeg2k gives you the best
113              compression it can without losing any quality.  Because  of  the
114              metadata  issue  described  above,  this  may  mean, for a small
115              image, the image actually expands.
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117              Note that though the Jasper library takes a compression  factor,
118              this option specifies a compression ratio.  The compression fac‐
119              tor is the multiplicative inverse of (1 divided by) the compres‐
120              sion ratio.
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122              Before  Netpbm 10.61 (December 2012), the default was a compres‐
123              sion ratio of 1, and if pamtojpeg2k could not  make  the  output
124              that  small,  it  just  made  it as small as it could, with zero
125              quality.  You know this is happening when you  see  the  warning
126              message, "empty layer generated."
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129       -verbose
130              This  option  causes pamtojpeg2k to issue informational messages
131              about the conversion process.
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134       -debuglevel=number
135              This option controls debug messages  from  the  Jasper  library.
136              pamtojpeg2k  passes  number as the debug level to the Jasper JPC
137              encoder.
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EXAMPLES

143       This example compresses losslessly.
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145         pamtojpeg2k myimg.ppm >myimg.jpc
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147       jpeg2ktopam will recreate myimg.ppm exactly.
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149       This example compresses the file to one tenth its original size, throw‐
150       ing away information as necessary.
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152         pamtojpeg2k -compression=10 myimg.pgm >myimg.jpc
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ABOUT JPEG-2000

157       JPEG-2000  is a format that compresses a visual image (or a similar set
158       of data) into a minimal number of bytes for  storage  or  transmission.
159       In that, its goal is similar to JPEG.  It has two main differences from
160       JPEG.
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162       One difference is that it does a much better  job  on  most  images  of
163       throwing  out  information  in order to achieve a smaller output.  That
164       means when you reconstruct the  image  from  the  resulting  compressed
165       file,  it  looks  a  lot closer to the image you started with JPEG-2000
166       than with JPEG, for the same  compressed  file  size.   Or,  looked  at
167       another  way, with JPEG-2000 you get a much smaller file than with JPEG
168       for the same image quality.
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170       The second difference is that with JPEG-2000, you decide how much  com‐
171       pression  you  want and the compressor adjusts the quality to meet your
172       requirement, whereas with JPEG, you decide how much  quality  you  want
173       and the compressor adjusts the size of the output to meet your require‐
174       ment.  I.e. with JPEG-2000, the quality of the result  depends  on  the
175       compressibility  of  the  input,  but with JPEG, the size of the result
176       depends on the compressibility of the input.
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178       With JPEG-2000, you can specify lossless compression,  thus  making  it
179       compete  with  GIF  and PNG.  With standard JPEG, you always lose some‐
180       thing.  (There are rumored to be variations of  JPEG  around  that  are
181       lossless, though).
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183       JPEG is much older than JPEG-2000 and far more popular.  JPEG is one of
184       the half dozen most popular graphics formats and virtually all graphics
185       facilities understand it.  JPEG-2000 is virtually unknown.
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187       There  is  no  compatibility between JPEG and JPEG-2000.  Programs that
188       read JPEG do not automatically read JPEG-2000 and vice versa.
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SEE ALSO

193       jpeg2ktopam(1), pnmtojpeg(1), ppm(1), pgm(1), pbm(1), pam(1),
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History

197       pamtojpeg2k was added to Netpbm in Release 10.12 (November 2002).
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DOCUMENT SOURCE

200       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
201       source.  The master documentation is at
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203              http://netpbm.sourceforge.net/doc/pamtojpeg2k.html
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205netpbm documentation            31 January 2014     Pamtojpeg2k User Manual(0)
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